The present invention relates to telecommunications in general and more particularly to the processing of audio signals such as telephone audio signals. Specifically, the invention provides an adapter card featuring a time-shared DSP resource, for use with a computing apparatus that provides call-related functions. In a specific example, the call-related functions can be voice-recognition, voice messaging and IP telephony, among others. The invention also provides a method and apparatus for processing calls by time-sharing a DSP resource. The invention further provides a digital signal processor featuring a switch capability coupled to a time-shared DSP resource.
Modern telephony brings to consumers a broad range of enhanced functions above the basic telephone service such as the ability to establish a communication link between two remote locations in a network. Specific examples of such enhanced call-related functions include voice recognition, IP telephony and voice messaging, automated call distribution, integrated voice response (talk-back to user) and text to speech conversion, among many others. The implementation of the enhanced call-related functions requires special manipulations of the audio signal on the line. A digital signal processor that is in the form of an integrated circuit capable of high-speed data processing is used to perform these manipulations. Normally, a single digital signal processor mounted on an adapter card installed in the telecommunication apparatus handling calls, such as a network switch or a PBX (Private Branch eXchange) is associated to a single call-related function and performs the audio signal processing when that call-related function is invoked. This form of implementation is not entirely satisfactory for cost reasons. The multiple adapter cards required for providing a wide range of enhanced services significantly increases the cost of the equipment.
In addition, multiple adapter cards increase the size of the telecommunication apparatus, which of course is undesirable. Also, upgrades on installed equipment are more difficult to implement. When a customer desired a new call-related function, he/she must purchase a new adapter card that often must be installed by a qualified technician. The installation is only possible if the telecommunication apparatus has free adapter card slots.
Therefore, there exists a need in the industry to provide systems capable to offering call-related functions at a lower cost than presently existing solutions and that make upgrades easier to implement.
In one aspect, the invention provides an adapter card for use with a computing apparatus capable of executing program elements for processing an audio signal and requiring a DSP resource. In a specific example, the program elements implement call-related functional units such IP telephony, voice recognition, and voice messaging, among others. The adapter card has a first interface for connection to at least one line carrying an audio signal and a switch that receives the audio signal from the interface and routes the signal toward a selected destination. A digital signal processor can receive an audio signal from the switch and perform desired manipulations on that audio signal. The digital signal processor provides time-shared services for the program elements executed by the computing apparatus.
The adapter card also has a second interface for connection to the computing apparatus. The switch is responsive to a control signal received from the second interface indicative of a request of a certain program element to gain access to a digital signal processor service, for directing an audio signal to the digital signal processor. The data issued by the digital signal processor as a result of the processing of the audio signal is made available to the program element for further processing.
In a specific example, the adapter card implements the functionality of a PBX (Private Branch eXchange) that enables users within an organisation to place calls to each other without going through the PSTN (Public Switch Telephone Network). In this form of implementation, the first interface receives a plurality of internal lines that connect to respective telephone sets. Also the interface receives one or more external lines connecting to the PSTN or to any other external network.
Under this specific example, the computing apparatus in which the adapter card is installed can be a server that executes the program elements implementing call-related functional units. When any one of those program elements executes to provide a certain call-related function, it will issue the necessary control signals to the switch on the adapter card such that the audio signal on which the function is to be performed will be directed to the digital signal processor. The latter manipulates the audio signal as required and transmits the results of manipulations to the program element for further processing. The digital signal processor is a time-shared recourse and in this specific example, a single digital signal processor is used to provide DSP services to a variety of call-related functional units.
In a different aspect the invention provides a call-processing apparatus comprising a line interface for connection to at least one line carrying an audio signal, a switch coupled to the interface and a digital signal processor capable to perform manipulations on the audio signal when the switch routes the audio signal to the digital signal processor. The call processing apparatus also comprises a plurality of call-related functional units for processing an audio signal at the line interface, the call-related functional units being capable of time-sharing the digital signal processor resource.
In yet another aspect, the invention provides a digital signal processor capable to perform core telephony functions and also providing time-shared DSP resources.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art on review of the following description of specific embodiments of the invention in connection with the accompanying figures.